Background: The incorporation of new drugs into induction, consolidation, and maintenance therapy is changing the treatment paradigm of MM.

Methods: At diagnosis, 402 pts (< 65 years) were randomly assigned to receive six MPR cycles (N=202) or tandem MEL200 (N=200). After MPR or MEL200, pts were further randomized, within each group, for no maintenance (N=204) or lenalidomide maintenance (N=198). A 2x2 factorial randomized trial was designed. The primary end point was PFS. An enrolment of 170 pts/arm was required to demonstrate a 15% improvement of PFS at 2 years (2-sides a = 0.05, 1- β 80%).

Results: After a median follow-up of 45 mos from diagnosis, the median PFS was 25 mos with MPR and 39 mos with MEL200 (p=.0002). Median PFS were 37.5 mos for maintenance and 25.7 mos for no maintenance (p=.0008). The 4-year OS from diagnosis was 71% with MPR and 72% with MEL200 (p=0.71), 76% for maintenance and 68% for no maintenance (p=.08). After a median follow-up of 32 mos from start of maintenance, the median PFS was for 41 mos for maintenance and 18 mos for no maintenance (p<.0001). The 3-year OS from start of maintenance was 81% for maintenance and 72% for no maintenance (p=.04).

Conclusions: MEL200 significantly prolonged PFS in comparison with MPR. Lenalidomide maintenance significantly reduced the risk of progression independently from the previous treatment. OS is similar between MPR and MEL200, with a trend for an improved OS in pts receiving lenalidomide as maintenance therapy.